The present invention relates to a device for indicating fading operation in a cinecamera.
Heretofore, in a cinecamera in which a galvanometer or a voltmeter is used to drive the diaphragm of the objective lens of the cinecamera through a control circuit connected to the meter so as to achieve the proper exposure while the automatic fading operation is effected by controlling the current flowing through the meter, the condition of advance of the fading operation is visually confirmed by observing the indication of the aperture of the diaphragm if such is provided in the camera, or a device is provided which includes a light emitting diode adapted to be lighted upon completion of the stopping-down of the diaphragm or the completion of the fading out so as to indicate the completion of the fading-out.
However, such a prior art device for indicating fading operation is not yet satisfactory for permitting the operator to carry out correct fading operation without wasteful or premature manipulation of the camera by indicating clearly each steps of advance in the fading operation and the operator is at all times uneasy in operating the camera for the fading operation.
The object of the present invention is to provide a novel and useful device for indicating fading operation in a cinecamera which is simple in construction and inexpensive and easy to adjust and yet avoids the disadvantages of the prior art device for indicating fading operation in a cinecamera.
The above object is achieved in accordance with the present invention by the provision of a device for indicating fading operation in a cinecamera having a control circuit adapted to receive a controlled output voltage such as the scene light indicating voltage corresponding to the scene brightness and a manually adjusted output voltage and to drive a diaphragm driving means of the camera so as to adjust the diaphragm aperture to a value set by the controlled output voltage, a capacity-resistor circuit connected to the diaphragm control circuit and adapted to selectively apply constant charging voltage to the diaphragm control circuit and discharge the charged voltage at constant rate, thereby permitting the control circuit to drive the diaphragm driving means correspondingly to the selectively charged or discharged voltage so as to continuously vary the aperture of the diaphragm with the lapse of time for effecting the fading-out and the fading-in, the device being characterized by a first comparator adapted to receive the output voltage of the capacitor-resistor circuit and the output voltage of the diaphragm control circuit to issue a signal when both the output voltages are made coincident with each other, a second comparator connected to the capacitor-resistor circuit adapted to issue a signal when the output voltage of the capacitor-resistor circuit reaches a constant charging voltage corresponding to the completion of the fading-out, and indicating means adapted to receive the output signals of the first and second comparator and indicate at least the completion of the fading-out as well as the completion of the fading-in.
The controlled output voltage to be applied to the diaphragm control circuit may be a scene light indicating voltage supplied from a scene light indicating voltage generating circuit including a photoelectric element so that, in the normal operation of the camera, proper exposure is achieved by the device.
The indicating means may include a light emitting element so that the indication is visually indicated.
Also, the indicating means may include a flag member driven by an electromagnet either of which or the image of which is moved into or removed from the field of view of the finder of the cinecamera according to the condition of the fading operation.